Shinichi Nakajima

Temperature dependence of the band gap in InAsyP1−y

The temperature dependence of the band gap in InAsyP1−y (y=0–0.67) has been determined by photoluminescence, x-ray diffraction, and absorption spectra measurements. We found that the measured data within the temperature range of 77–300 K can be expressed by the equation proposed by O’Donnell and Chen. The band gap at 77 K is given by Eg=1.407−1.073y+0.089y2, while the compositional dependence of the band gap observed at 300 K, agrees with the values previously reported. We confirmed that changes in temperature caused a slight change in the bowing parameters, and hence found that the band gap temperature dependence of InAsyP1−y (y=0–1) varies very little with changes in composition (2.5–3.5×10−4 eV/K).

Spectroscopic detection of ammonia using diode-pumped difference-frequency generation

Use of photons for in-situ measurements of various objects provides a number of benefits, such as precise real-time measurement with no effect on the measured objects. Our research aims to develop an in-situ measurement technology that uses the benefits of photons and is ideal for applications in production lines. We succeeded in developing a tunable laser beam source to obtain the spectral line width of 5 MHz and a continuous wavelength sweep bandwidth of 200 nm, thus achieving our initial target. We believe that these characteristics are sufficient for use in absorption spectroscopy measurement of gases. For a 2.5 - 2.7 micrometer- band quantum infrared photo detector, we achieved the initial target of D* equals 1 to 3 X 1011 cmHz1/2/W (at room temperature). For a 3 - 10 micrometer-band quantum infrared photo detector, we performed a study on designing an InAsP/InP multi-quantum well light-absorbing layer.